Some community activists are trying to put the brakes on a billionaire media mogul's plans to build a $150 million park atop a pier on the Hudson River. Michael Scotto filed the following report.

It's a common sight on the Hudson River: Robert Buchanan in his rowboat.

The New School professor says he's so passionate about the Hudson, he's suing to stop construction of a $150 million futuristic park atop a sloping pier, funded largely by media tycoon Barry Diller.

Buchanan took us to the site of what will be called Pier 55, a public space off Gansevoort Street that will replace the much smaller Pier 54.

Scotto: So where the boat is now?
Buchanan: Would be covered by a platform. And so this embayment that we're in would no longer be an embayment. It would be built-ins.

Buchanan is a front man in a David versus Goliath battle against what critics call "Diller Island." They claim the billionaire got his way with state and local officials without much debate about how the pier will affect the environment and the boaters who will lose water access.

"I think they should have involved stakeholders, people like me who use the water a lot, in initial discussions," Buchanan said. "And I think the plan was announced as a done deal. The design was announced as final."

The Hudson River Park Trust says it followed the rules in approving the project, which consists of 2.7 acres of landscaped knolls, trees and a performing space above the river.

"There was a robust environmental assessment done. We went beyond what was required by law by putting it out on our website," said Noreen Doyle, executive vice president of the Hudson River Park Trust. "There was a public hearing that we held. Community Board 2 held two public hearings about this."

They insist this alcove has never really been used for recreation.

Scotto: You're not looking out, they say, for the thousands and thousands of people who are going to come here and use that park. That you're really just looking out for yourself and a handful of boaters.
Buchanan: I like to think that I'm looking out for the river.

A court hearing is expected in September. Construction is supposed to begin early next year.